Classification or separation of particles by size is an important commercial operation in several industries. In classification or separation, a stream of mixed size particles is divided into a stream of relatively coarse particles and a stream of relatively fine particles. Several methods have been developed to separate particles including: dry-screening devices, wet-screening devices, hydraulic-settling classifiers, hydraulic-cyclone classifiers, pneumatic-settling classifiers and pneumatic-rotary vane classifiers. The particular type of classifier utilized in a specific industrial application depends upon the size distribution of the particles, shape of the particles, weight of the particles, volume of the particles to be processed and other factors particular to the particle to be separated.
Dry screening consists of simply passing particles over a screen having a known number of openings per linear unit or per unit area and dividing the particles into particles that passed through the screen and particles that did not pass through the screen. Wet screening adds water to the particles to improve the passing rate of particles through the screen. Pneumatic and hydraulic classification operates by balancing the forces of gravity with the forces of pneumatic or hydraulic drag. Coarse particles generally have a higher mass to surface area ratio then fine particles. This property is utilized in pneumatic and hydraulic separation to classify mixed size particles. The mixed size particles are placed in a moving fluid which transports the heavier coarse particles to one location and transports the lighter fine particles to a different location.
The type of commercial separator chosen to separate generally spherical particles of ferronickel from ferronickel dust produced from the decomposition of nickel carbonyl and iron carbonyl was a dry-screening device. Unfortunately, the dry-screening device did not adequately remove the dust or very fine particles of ferronickel. The resulting product was a less than desirable dusty product of ferronickel particles or powder. This dust interferes with the cleanliness of industrial applications of the ferronickel. Additionally, dry screening of the ferronickel particles is noisy, adding undesirable noise pollution to the work environment.